PTN technology is essentially a packet-based routing architecture to provide multi-service technical support. It is a more suitable for IP service transmission technology, while inheriting the traditional advantages of optical transmission, including a good network scalability, a rich operation and maintenance (OAM), fast protection switching and clock transmission capability, high reliability and safety sex, the whole concept of network management, end to end service configuration and precise alarm management. These advantages PTN is the traditional router and Enhanced Ethernet technology can not match, which is distinct from the important attributes of both. We can understand the concept of PTN technology from the following four aspects.

OADM equipment in long haul and metro networks are useless.
◆ In the trunk applications, OADM device of choice up and down business intermediate nodes.

The main function of OADM is separated from the multi-wavelength channels or insertion of one or more wavelengths, there are fixed and reconfigurable two types.

T-MPLS (Transport MPLS) is a connection-oriented packet transport technology. In the transport network, the client signal is mapped into the MPLS frame and use MPLS mechanisms (such as label switching, the label stack) forwards, while it increases the basic functions of the transport layer, such as connectivity and performance monitoring, survivability (protection and restoration), management and control plane (ASON/GMPLS).

Active optical network central office equipment (CE) and remote equipment (RE) connected via active optical transmission equipment. Transmission technology is the backbone network SDH and PDH technologies have been widely adopted, but the main SDH technology. Remote device mainly to complete the collection business, interface adapter, multiplexing and transmission. Central office equipment mainly to complete the interface adapter, multiplexing and transmission. In addition, the central office equipment to the network element management system also provides network management interface. In the actual construction of the access network, active optical network topology is typically star or ring. Active optical network technology has the following characteristics:

Active optical access technology Application bandwidth demand, high security communication enterprises and institutions access. It can also be used in the feeder section and wiring section of the access network, and mixed with other access technologies based on the use of wireless or copper wires.

AON (Active Optical Network) is a signal during transmission, the transmission network from the central office equipment to the use of the photoelectric conversion devices, active optoelectronic devices and fiber optic transmission equipment and other active optical fiber between user allocation unit. Active optical device comprises a light source (laser), optical receivers, optical transceivers, optical amplifiers (fiber amplifiers and semiconductor optical amplifiers).

Optical Access Network refers to the optical fiber as the transmission medium of the network environment. Technically fiber access network can be divided into two categories: active optical network (AON) and passive optical network (PON). Active optical network can be divided into SDH and PDH's AON; passive optical network can be divided into narrowband and broadband PON.

SDH its obvious superiority transmission network has become the mainstream of development. SDH technology and some advanced technology, such as optical wavelength division multiplexing (WDM), ATM technology, Internet technology (Packet over SDH), so that the role of SDH network is growing. SDH has been included in various countries in the 21st century high-speed communications network application project is the development direction of the telecommunications industry recognized digital transmission network, with great commercial prospects.

OTN's intelligent optical network will provide the ideal solution for the transmission of large-granule broadband services. Inter provincial transport network main trunk transport network, provincial trunk transport network, metro (local) transport network structure, while the Metro (local) transport network can be further divided into the core layer, convergence layer and access layer. SDH relative terms, the biggest advantage of OTN technology is to provide scheduling and delivery of large particles of bandwidth, therefore, at different levels whether to adopt OTN network technology, depending on the size of the primary particles dispatch service bandwidth. According to the network situation, primarily particles inter-provincial trunk transmission network, the province trunk transport network and metropolitan area (local) transport network core layer of scheduling is generally Gb / s and above, therefore, these levels can be given priority and scalability advantages OTN technology to build better. For Metro (local) transport network convergence and access layer, when major scheduling particles reach Gb / s order of priority can also be constructed using OTN technology.